1. The Field of the Invention
The present invention relates to power management in computer peripheral devices, and more specifically, power management of peripheral devices employing various cognitive levels for purposes of power conservation.
2. The Relevant Technology
Computers from their original inception have undergone significant evolutionary changes both in operation and configuration. For example, computers originally were largely physically bulky in size and inefficient in power consumption, resulting in fixed site devices requiring constant interconnection with generally limitless power sources. As electronics were integrated, the physical dimensions of computers were reduced even to small portable form factors. For a computer to be truly portable, it became necessary for the computer to utilize an independent portable power source such as a battery. Those familiar with battery technologies as they relate to portable computers appreciate the tension between a desirable small form factor and an also desirable limitless power source. As these two ideals met reality, considerable frustration was born.
Significant re-engineering and refinement of computers relating to their appetite for operating power continues as does the ongoing refinement of portable power sources, namely batteries. Many approaches such as powering only essential components have also been undertaken yielding great success toward conserving available portable power.
Other advances in computers relate to a computer""s extensibility or its ability to extend its performance or capabilities through the use of interconnections with other devices including other computers. Such interconnections are commonly known as xe2x80x9cnetworksxe2x80x9d having various topologies and standards known by those of skill in the art. Since the specifications and standards for these various network topologies evolves and computational capabilities advances, computer developers have created various standard interfaces through which replaceable network interface modules capable of directly interacting with the networks may be utilized. These network interface modules or cards have a standard interface for coupling to the computer and another interface customized to interact with the network standard. In order to facilitate the translation of data from the computer to the network, these network interface modules or cards are also comprised of electronic circuitry that possess their own appetite for operational power.
Those of skill in the art appreciate the various standards for these interface cards that include the PCMCIA, PCI and mini PCI interface card standards. These interface cards or peripherals traditionally physically and electrically interface with a computer via card slots located in the computer. Since these peripheral cards become appendages to the computer, they rely on the computer to provide operational power. Such a dependency further burdens the limited operational power resident or available to the computer.
In further attempts by computer designers to manage the available power, computer designs have resorted to supplying operational power to peripheral modules only when the modules are active and interacting with the network on behalf of the computer. While such an xe2x80x9call-or-nothingxe2x80x9d approach proves advantageous to the conversation of portable power resources, the wholesale shutting-down of a network interface card virtually isolates the computer from other network resources and ignores all interaction of the network with the computer. In further attempts to address this dire situation, peripheral card designs have attempted to partition more essential and less-essential network interface circuitry on the peripheral card and apply power to only those portions of the circuitry that directly listen for network commands. However, such approaches have traditionally required the computer to be originally powered and then undergo significant configuration followed by the selective removal of power to the less essential portions of the interface card circuitry.
There is also great interest in the computer networking world to develop an approach that enables a computer user to have their computer operably configured to a network through a remote configuration means that only requires the user to physically connect their computer to the network and to main power. Such an approach would require the computer network interface to continually monitor the network traffic for relevant configuration information.
Therefore, it would be an advancement in the art to develop a power management circuit for use on a interface card or peripheral module that could autonomously determine a low power configuration as assigned and self configured to that setting thereby autonomously assuming a low or reduced power consumption state without significant computer interaction.
The present invention provides low-power approach to determining when the network monitoring portion of the network circuitry should remain powered and a low-power approach to asserting such power to the circuitry. There is interest in supporting emerging technology relating to simplification and remote control of computers on a network. The present invention provides a solution to supporting functionality such as what is becoming commonly known as xe2x80x9cWake-On-LAN (WOL)xe2x80x9d or xe2x80x9cPlug In and Go (PIG)xe2x80x9d functionality. Such functionality requires power to the network card such as the mini PCI LAN/Modem card upon the assertion of AC power to the computer. In a preferred embodiment, the network card is comprised of a non-volatile memory device containing configuration parameters dictating whether the network card should implement these streamlined configuration functionality. In order to support such functionality, the network card needs to switch power to evaluation circuitry that can read and evaluate the configuration parameters, and when the configuration parameters specify the use of this functionality, then sustain the assertion of power to the network monitoring portion of the network interface circuitry.
The power management circuit of the present invention is comprised of two main sections, the power switch circuit and the power switch control circuit. The power switch, in the preferred embodiment, utilize P-channel MOSFETs that have a very low xe2x80x98ONxe2x80x99 resistance in order to minimize the voltage drop across the switch devices. Two series configured MOSFET switches are place on each input power path to prevent back powering through the intrinsic diodes in the MOSFET. The power switch control circuit controls the power switch circuit for asserting power to the network monitoring portion of the network circuitry under two conditions: (i) upon initial application of power to the computer when the configuration parameters need to be evaluated and (ii) when an evaluation of the network configuration parameters specify that monitoring functionality such as WOL or PIG are requested.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The features and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.